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MM: Fachverband Metall- und Materialphysik

MM 6: Topical Session: TEM-Symposium - Joint Session with MI II

MM 6.2: Hauptvortrag

Montag, 11. März 2013, 12:15–12:45, H4

Structural Characterization of nc-Si / SiO_x based quantum superstructures for the solar cell application by aberration-corrected high resolution electron microscopy — •Maryam Beig Mohamadi¹, Birger Berghoff², and Joachim Mayer^1,3 — ¹Central Facility for Electron Microscopy, RWTH Aachen, Ahornstrasse 55, 52074 Aachen, Germany — ²Institute of Semiconductor Electronics, RWTH Aachen University, Sommerfeldstr.24, 52074 Aachen, Germany — ³Peter Gruenberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Research Centre Jülich, D-52425 Jülich, Germany

In the frame of SINOVA project, two nano-structured systems were investigated, a-Si/SiO_x and SiO_x/SiO₂ multilayer systems. After annealing the sample, Si nano-crystals formed within an amorphous SiO₂ matrix. The morphology and distribution of the nc-Si precipitates within the amorphous layer, their nucleation and growth kinetics, the thickness of conducting layers and the diffusion of O or Si through interfaces were analyzed by high resolution transmission electron microscopy, energy filtered transmission electron microscopy and electron energy loss spectroscopy. We employed aberration-corrected TEM microscopes to reveal the crystalline structure and the chemical distribution of Si on the atomic scale. It is observed that the mean size of the QDs and their distribution in the dielectric matrix changes by the initial thickness of the SiO_x layer. The kinetics of the formation of nc-Si precipitates in Si-rich layers sandwiched between barrier layers was studied as a function of stacking period and oxygen content in the system.